Rotavirus is the most common cause of severe diarrhea among infants and young children (Dennehy P H, 2000), and is one of several viruses that cause infections often called stomach flu, despite having no relation to influenza. It is a genus of double-stranded RNA virus in the family Reoviridae. There are five species of this virus, referred to as A, B, C, D, and E (ICTV Virus Taxonomy: 2009 Release). Table 1 provides a summary of known rotaviral proteins. Rotavirus A, the most common, causes more than 90% of infections in humans. The virus is transmitted by the fecal-oral route, and infects and damages the cells that line the small intestine and causes gastroenteritis. In addition to its impact on human health, rotavirus also infects animals, and is a pathogen of livestock (Dubovi E J, 2010).
For example, according to a recent study, rotavirus was commonly found (65%) in the feces or intestinal contents from pigs with diarrhea. The majority of animals were infected by single group (A, B, C) although concurrent infection by more than one rotavirus group does occur (Yoon, K J, Epidemiology of rotaviruses, ISUVDL submissions, 2010-2011, Iowa State). Nearly one-third of animals were infected by at least Group C Rotavirus. Until now, prevention of rotavirus in porcines had involved rather arcane practices, such as feeding infected piglet tissue to healthy pigs. This practice was necessitated because Group C rotavirus cannot be grown in vitro, thus preventing the production of conventional inactivated/attenuated whole-virus vaccines. Thus, there is a clear and urgent need for safer and more effective preventative measures.
TABLE 1Rotavirus protein summarySize (bp, basedRNA Segmenton Human RotaMolecularCopies per(Gene)C strain)Proteinweight kDaLocationparticleFunction13309VP1125At the vertices<25RNA-dependentof the coreRNA polymerase22736VP2102Forms inner shell120Stimulates viralof the coreRNA replicase32283VP388At the vertices<25Guanylyl transferaseof the coremRNA capping enzyme42166VP487Surface spike120Cell attachment,virulence51353NSP159Nonstructural05′RNA binding61350VP645Inner Capsid780Structural and species-specific antigen71270NSP337Nonstructural0Enhances viral mRNAactivity and shut-offscellular protein synthesis81063NSP235Nonstructural0NTPase involved inRNA packaging91037VP7, VP738, 34Surface780Structural andneutralization antigen10730NSP420Nonstructural0Enterotoxin11613NSP5 NSP622Nonstructural0ssRNA and dsRNA bindingmodulator of NSP2
An alternate approach would be to produce vaccines comprising immunogenic rotavirus subunit proteins or antigens. At time of filing this disclosure, inventors are aware of no references describing methods of producing rotavirus subunit vaccines (autogenous or otherwise) to immunize porcines against rotavirus, particular the Group C variety. The following patents and applications summarize relevant rotavirus prior art, with emphasis on subunit-based vaccines.
U.S. Pat. No. 7,790,178 (to Intervet) describes trivalent vaccines, which includes inactivated canine rotavirus.
U.S. Pat. No. 7,311,918 & U.S. Pat. No. 6,589,529 (to Children's Hospital Ohio) describe a recombinant rotavirus fusion protein comprising a VP6 protein fragment, intended for vaccinating humans. Mouse data indicated the vaccine generated an immune response directed against the VP6 fusion protein.
U.S. Pat. No. 6,867,353 (to Exploregen) generally describes expression of a cDNA fragment encoding human rotavirus structural protein using transformed tomato.
U.S. Pat. No. 6,716,431 (to Wyeth, now Pfizer) describes alternate forms of NSP4 (i.e. SNPs resulting in amino acid changes), which still retain antigenicity, but exhibit reduced cytotoxicity.
U.S. Pat. No. 6,673,355 & U.S. Pat. No. 6,210,682 (to Baylor College of Medicine) relate to use of NSP4 and fragments thereof (NSP4 114-135, NSP4 120-147, NSP4 112-174, or NSP4 112-150) as a prevention and/or treatment of rotaviral disease. Compositions including an enterotoxin adjuvant are also described. U.S. Pat. No. 5,891,676 & U.S. Pat. No. 5,827,696 (also to Baylor) describe baculoviral expression of rotavirus VP2 and VP7, respectively.
U.S. Pat. No. 6,187,319 (to University of Mass.) generally relates to methods for producing immune responses in animals against a first rotavirus by administering an isolated VP6 polypeptide of a second rotavirus that infects a different species than the animal to be vaccinated.
U.S. Pat. No. 5,298,244 (to University of Saskatchewan) describes assembled viral particles having VP4, VP6, and VP7.
US20110171316 (to US Health and Human Service) describes a recombinant human rotavirus group C virus-like particles.
US20100047763 (to Goes et al.) discloses plasmid DNA encoding rotavirus proteins for use in diagnostic kits.
U.S. Pat. No. 5,186,933 (to Baylor College of Medicine) discloses expression of rotavirus genes, particularly VP3 and VP7) using a baculovirus system.
Until their present disclosure, inventors are aware of no effective porcine rotavirus subunit vaccine prepared by expressing rotavirus type C antigens in E. coli. Further, no methods for producing safe and effective vaccines for porcines have been disclosed, and thus it is an object of the instant disclosure to provide such vaccines.